Hull construction

ABSTRACT

A hull construction for watercraft wherein means are provided for inducing the flow of a plurality of bubbles along the outer surface thereof to reduce frictional resistance to the passage of the watercraft through the water.

United States Patent Swanson [4 1 Mar. 21, 1972 54 HULL CONSTRUCTION 1,894,256 1/1933 De Ganahl et al ..1 14/67 [72] Inventor: Norman Swanson, Conover Wis. 2,754,791 7/1956 Nieding ..114/67 [73] Assignee: Veritas International primary Examiner Andl-ew n 22 Filed; Ju|y 31 19 9 Attorney-Francis T. Drumm [21] Appl. No.: 846,521 ABSTRACT j A hull construction for watercraft wherein means are prol. ..1

g u vided for inducing the flow of a plurality of bubbles along the 581 Field of Search ..114/67.1 Outer suface there m reduce mama fesisance the passage of the watercraft through the water. R i t d [56] e erences Cl e 2 Claims, 9 Drawing Figures UNITED STATES PATENTS 1,840,185 1/1932 Cable ..1 14/67 X AIR -24 MOVEMENT OF HULL WATER LINE PATENTEDMAHZI 1972 3,650,235

sum 1 or 2 INVENTOQ A U/QMAA/ SWAA SOA ATTORNEY HULL CONSTRUCTION SUMMARY A hull construction for watercraftsuch as boats, seaplanes or the like in which the motion of the watercraft through the water effects the production of a plurality of bubbles along the exterior hull surface. In the preferred embodiment, a plurality of longitudinally extending laterally spaced conduits are disposed on the outer hull surface. Each of the conduits has a plurality of outwardly extending longitudinally spaced projections at each side thereof, each of the projections terminating in an opening. Air is induced to flow into the conduits and thence into the space between adjoining conduits in the form of a plurality of minute bubbles. These bubbles are created by the velocity of the air flowing through the conduits, pursuant to Bernoullis theorem. This invention is an improvement over the invention described and claimed in the patent of Carl De Ganahl et al., US. Pat. No. 1,894,256, Jan. 10, 1933. In that patent, applicant describes a hull construction of the same general type as the present invention but describes a hull construction having an auxiliary outer wall provided with a plurality of bent portions 13 which extend upwardly towards the main wall of the boat. A disadvantage of his construction is that the space between the outer and the auxiliary wall fills with water and adds to the normal hull resistance. In addition, the elements 13 are not positioned to take advantage of Bernoullis theorem.

Other advantages of the invention will become apparent as the description proceeds with reference to the accompanying drawings wherein:

FIG. I is an elevational view of a seaplane embodying the hull construction of the present invention, the seaplane being illustrated in waterborne condition;

FIG. 2 is an enlarged elevational sectional view taken substantially on line 22 of FIG. I;

FIG. 3 is a longitudinal sectional view of the hull construction of FIGS. I and 2;

FIG. 4 is a bottom view of the hull of FIGS. I, 2, and 3;

FIG. 5 is an elevational sectional view of a modified form of the present invention;

FIG. 6 is an enlarged bottom plan view of the hull construction of the form ofthe invention illustrated in FIG. 5;

FIG. 6a is an enlarged sectional view taken substantially on line 611-60 of FIG. 6;

FIG. 6b is a view similar to FIG. 6a but showing a modified form of the invention;

FIG. 7 is an elevational sectional view of a hull construction of the prior art.

The present invention relates basically to the provision of a hull construction characterized by a hull wall having secured thereto means defining a plurality of longitudinally extending transversely spaced channels or conduits, each having a plurality of longitudinally spaced openings, each defined by a downwardly extending projection to effect the flow of air into the slipstream of the hull in a manner that a plurality of tiny bubbles are formed and the frictional resistance of the hull is diminished. In particular, applicant contemplates the utilization of the Bernoulli principle to effect this flow of bubbles. According to that principle, a fluid pressure is inversely proportional to the square of the fluid velocity. In this instance, there is secured to the outer wall a plurality of longitudinally extending, transversely spaced channels with a plurality of downturned projections each defining an opening through which air flows in response to a pressure differential. This pressure differential is a function of the speed of movement of the vessel through the water since the water adjacent the outer shell or wall is at a reduced pressure because of the fact that the velocity of the water is increased. Furthermore, this pressure differential is enhanced by the fact that each of the projections functions as a hydroplane.

Referring now to the drawings and more particularly to FIG. I, the hull construction of the present invention is illustrated as applied to a seaplane, it being understood that it is utilizable in any type of watercraft in which the diminution of the frictional resistance of the water is desired. The watercraft is illustrated as having a hull 10 to which is secured an outer covering 14, preferably of metal such as aluminum or the like. In the preferred embodiment, the wall covering is illustrated-as being corrugated to form a plurality of longitudinally extending V- shaped channels 16 separated by longitudinally extending grooves 18. Each of the channels I6 is formed at the sides thereof with a plurality of pairs of longitudinally spaced projections 20 extending into the adjacent groove 18 and defining an opening 22. The projections 20 are preferably integral with the covering 14 and are desirably stamped so that the projection is formed at the same time as the opening 22.

Referring now to FIG. 3, means are provided to afford access of ambient air to each of the channels 16. In this figure, there is illustrated one means for effecting this end. The left most projection 20 is disposed sufficiently forwardly of the craft so that it rises out of the water when the speed of the craft reaches a predetermined value. When this occurs, ambient air enters the channels 16 in the manner illustrated by the arrows. Entrance of water into the channels 16 is precluded by caps 21. According to an important feature of the present invention, this air is withdrawn through the plurality of openings 22 by the velocity of the hull as the craft passes through the water. This is attained because of the existence of a low-pressure zone on the outer surface of the wall 14 caused by the flow of water around the projections 20. This flow causes a low-pressure zone behind each of the projections 20 which further tends to produce a low-pressure zone. Thus, the movement of the craft through the water affords such a pressure development that a relatively large volume of air is caused to flow through the openings 22 to produce a relatively large quantity of tiny bubbles in the grooves 18. Applicant has established by actual test that the takeoff time of a seaplane can be reduced substantially over that of a standard hull construction of the same seaplane without the hull construction of the invention. Applicant believes that this effect is obtained by two separate applications of the Bernoulli principle. Firstly, the water molecules adjacent the hull of any watercraft are moving at a relatively high velocity with respect to the adjacent molecules. The addition of the projections 20 enhances the low-pressure, high-velocity effect to produce the plurality of bubbles with a consequent effective surface tension substantially below that existing in a conventional hull construction.

Referring now to FIG. 5, applicant also contemplates the positive pumping of air into the channels 16 to enhance the flow of air through the openings 22. In the illustrated embodiment, air flows through a conduit 24 from an air scoop or the like and passes into the channels 16. As the hull moves to the left, as viewed in FIG. 5, the air pressure in the channels 16 is increased, thus enhancing the flow of air through the openings 22.

When the present invention is used on an amphibious aircraft as illustrated and the aircraft is at rest, the channels of the invention assume approximately the position illustrated in FIG. 3. As the aircraft moves into the water, the front of the hull rises to the point where two-thirds of the hull is out of the water and one-third of the hull is in the water. In this condition, air is freely available to flow into the channels in large quantities for the production of great quantities of bubbles. Applicant has found that with the use of the hull construction of the present invention, he is able to effect a takeoff from a body of water with approximately 300 feet less taxying distance than the identifying aircraft without the present hull construction. Indeed, the resistance to takeoff approximates that of a grass landing strip in which the aircraft is utilizing conventional landing wheels.

FIG. 6a illustrates an enlarged view of a modified form of the invention in which the covering 14 is eliminated and in which the channels 16 are formed by a plurality of individual members 15 each having outwardly extending flanges 17 which may be secured to the hull 10 by any suitable means such as welding, riveting or the like.

FIG. 6b illustrates a further modified form of the invention in which the hull 10a is formed of fiber glass or the like and in which the channels 161: are formed integral with the hull. Projections a are formed in the sides of the V-shaped members and terminate in openings 22a. The channels 16 are completed by a double hull member 10b. I

In FIG. 7 is illustrated the construction of the prior art in which a plurality of projections extend above the level of the outer hull wall. This construction will not produce the Bernoulli effect and the production of bubbles is negligible.

The hull construction of the present invention exhibits important advantages over conventional hulls. Applicant has established that the takeoff time of a particular seaplane can be reduced as much as 35 percent by the use of the hull construction of the present invention. This result is obtained by the use of the Bernoulli principle to enhance the velocity of the water immediately adjacent to the hull.

I claim: I

1. A hull construction for watercraft comprising a main wall, an auxiliary wall secured to said man wall, said auxiliary wall having a plurality of longitudinally extending channels defining a plurality of longitudinally extending grooves, a plurality of projections formed in said channels, said projections extending outwardly from said channels and defining a plurality of openings whereby air in said channels is induced to flow through the openings defined by said projections to create a plurality of minute bubbles in said grooves to diminish the frictional resistance of the water with respect to the watercraft, said channels being substantially V-shaped and said tions being formed on the sides of said channels.

2. A hull construction for watercraft comprising a main wall, an auxiliary wall secured to said main wall, said auxiliary wall having a plurality of longitudinally extending channels defined by a plurality of longitudinally extending grooves extending inwardly from said auxiliary wall, a plurality of projections extending outwardly from said channels and defining a plurality of openings whereby air in said channels is induced to flow through the openings defined by said projections to create aplurality of minute bubbles in said grooves to diminish the frictional resistance of the water with respect to the watercraft.

projec- 

1. A hull construction for watercraft comprising a main wall, an auxiliary wall secured to said man wall, said auxiliary wall having a plurality of longitudinally extending channels defining a plurality of longitudinally extending grooves, a plurality of projections formed in said channels, said projections extending outwardly from said channels and defining a plurality of openings whereby air in said channels is induced to flow through the openings defined by said projections to create a plurality of minute bubbles in said grooves to diminish the frictional resistance of the water with respect to the watercraft, said channels being substantially V-shaped and said projections being formed on the sides of said channels.
 2. A hull construction for watercraft comprising a main wall, an auxiliary wall secured to said main wall, said auxiliary wall having a plurality of longitudinally extending channels defined by a plurality of longitudinally extending grooves extending inwardly from said auxiliary wall, a plurality of projections extending outwardly from said channels and defining a plurality of openings whereby air in said channels is induced to flow through the openings defined by said projections to create a plurality of minute bubbles in said grooves to diminish the frictional resistance of the water with respect to the watercraft. 